Determination of the orientation of CuCl nanocrystals in a NaCl matrix

Fröhlich, D.; Haselhoff, M.; Reimann, K.; Itoh, Tadashi

doi:10.1016/0038-1098(95)00051-8

Cited by 48 publications

(19 citation statements)

References 17 publications

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“…It has been mentioned above that the crystal axis of CuCl nanocrystals and that of the NaCl matrix are be parallel to each other (Fröhlich et al, 1995). The shape of the nanocrystals has rarely been studied.…”

Section: Discussionmentioning

confidence: 99%

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Small-angle X-ray scattering study of the growth kinetics of CuCl nanocrystals in NaCl

Kranold¹,

Kriesen²,

Haselhoff³

et al. 2003

J Appl Cryst

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The precipitation of CuCl nanocrystals in a NaCl matrix has been studied by time-resolved small-angle X-ray scattering. The experimental results suggest that the nucleation process is accelerated by lattice defects of the matrix remaining in the NaCl lattice after the dissolution of previous nanocrystals at high temperature. The evolution of structural parameters calculated from the scattering curves, such as volume fraction, mean radius and particle number density of the nanocrystals, is discussed in terms of a classical phase separation process but with specific concern for the effect of elastic strains. It was found that Ostwald ripening is effective during the whole period of observation. The effect of elastic strains results in an increase of the critical radius and a decrease of the coarsening rate. The results of the scattering experiments confirm the miscibility gap data determined by exciton spectroscopy.

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Section: Discussionmentioning

confidence: 99%

“…Both crystalline structures, CuCl as well as NaCl, are cubic and the crystal axes of the CuCl nanocrystals and the NaCl matrix are parallel to each other (Fröhlich et al, 1995). Thus, there is no reason that the anion sublattice collapses during the nucleation of nanocrystals.…”

Section: Introductionmentioning

confidence: 99%

Small-angle X-ray scattering study of the growth kinetics of CuCl nanocrystals in NaCl

Kranold¹,

Kriesen²,

Haselhoff³

et al. 2003

J Appl Cryst

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“…Using two-photon spectroscopy and exploiting selection rules of the ͑direct͒ exciton, most recently a uniform orientation of the crystal lattice was also found in case of CuCl NC's in NaCl. 20 Similarly, for the indirect exciton in silver halide ͑AgCl and AgBr͒ NC's selection rules may provide additional information. This demonstrates that, apart from the already mentioned advantages, the crystalline matrix is far superior to the formerly investigated micelle preparations in which the NC's were statistically oriented.…”

Section: Discussionmentioning

confidence: 99%

Exciton self-trapping in AgCl nanocrystals

et al. 2000

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Self-trapping of excitons is reported in AgCl nanocrystals embedded in a crystalline KCl matrix. The particles, observed by atomic force microscopy, have radii of several nanometers. Due to the spatial confinement only recombination of the self-trapped exciton ͑STE͒ is observed. STE(Br Ϫ ) and donor-acceptor pair recombination are absent. The time and temperature behavior of the emission is found to be significantly different from that in bulk AgCl. It is concluded that this is due to different self-trapped exciton configurations: The diffuse electron is spatially confined and centered in the nanocrystal whereas the compact hole, selftrapped at different lattice sites, causes variations in wave-function overlap in the different STEs. Optically detected magnetic resonance measurements reveal changes in g-values and a decrease by a factor of two in the magnitude of the zero-field splitting of the triplet state. They also demonstrate that the AgCl nanocrystal lattice axes are oriented along the axes of the KCl matrix.

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“…14 However, only in a crystalline matrix can CuCl nanocrystals show a common orientation as recently demonstrated by two-photon absorption experiments. 15 Therefore, in doped alkali halides the anisotropy of the embedded nanocrystals can be observed, but not in doped glasses. Another motivation for the study of CuCl in a crystalline matrix was the investigation of the elastic interaction between nanocrystals and the surrounding lattice.…”

Section: Introductionmentioning

confidence: 99%

Nanocrystal growth in alkali halides observed by exciton spectroscopy

Haselhoff

Weber

1998

Phys. Rev. B

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We have developed a method to study the growth of CuCl and CuBr nanocrystals in alkali halides by in situ absorption spectroscopy. Exciton lines are used as a signature of crystallinity and a broad absorption peak measures the number of Cu ϩ ions. The mean radius R and the concentration x cr of nanocrystals are determined simultaneously, which in turn enables the determination of the particle density N of crystals as a function of time. Neither the size-distribution function nor R(t) follow the prediction of the classical growth theory. x cr (t) reveals two different growth mechanisms, one for high and one for low growth temperatures. N(t) demonstrates that the growth of big crystals at the expense of small crystals happens from the beginning of the growth process. This result contradicts the traditional view of Ostwald ripening as a final stage of precipitation and stresses the dynamical character of cluster growth. The experimental data are described by a set of empirical parameters that can be used as a guide for controlled growth of CuCl nanocrystals in NaCl. The smallest nanocrystals detected by exciton spectroscopy consist of 50 unit cells. The kinetic properties of KCl and NaBr crystals doped with CuCl and CuBr are very similar to those observed in NaCl doped with CuCl.

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Determination of the orientation of CuCl nanocrystals in a NaCl matrix

Cited by 48 publications

References 17 publications

Small-angle X-ray scattering study of the growth kinetics of CuCl nanocrystals in NaCl

Small-angle X-ray scattering study of the growth kinetics of CuCl nanocrystals in NaCl

Exciton self-trapping in AgCl nanocrystals

Nanocrystal growth in alkali halides observed by exciton spectroscopy

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